Aqueous metal treatment composition

ABSTRACT

An aqueous metal surface treatment composition that includes (A) an aqueous dispersion of a phenolic novolak resin that includes water and a reaction product of a phenolic resin precursor, a modifying agent and a multi-hydroxy phenolic compound wherein the modifying agent includes at least one functional moiety that enables the modifying agent to react with the phenolic resin precursor and at least one ionic moiety, (B) an acid and, optionally, (C) a flexibilizer. According to one embodiment the modifying agent is an aromatic compound. According to another embodiment the ionic moiety of the modifying agent is sulfate, sulfonate, sulfinate, sulfenate or oxysulfonate and the dispersed phenolic resin reaction product has a carbon/sulfur atom ratio of 20:1 to 200:1.

[0001] This application claims benefit of U.S. Provisional ApplicationNo. 60/072,782, filed Jan. 27, 1998.

BACKGROUND OF THE INVENTION

[0002] The present invention relates to an aqueous autodepositablecomposition that is useful as a metal surface treatment.

[0003] It is well-known that metal surfaces are subject to corrosive andchemical degradation. This degradation has been combated by theapplication of various treatments to the metal surface. Conversioncoating of the metal surface is one such treatment. Conversion coatinggenerally involves treating the surface with chemicals that form a metalphosphate and/or metal oxide conversion coating on the metal surface.The conversion coating provides protection against corrosion and canenhance adhesion of any subsequent coatings. Phosphatizing is awell-established conversion process. However, phosphatizing suffers fromseveral drawbacks. It is a complex multistep process that is capitalintensive, requires close monitoring and can generate significantamounts of waste sludge. In addition, phosphatizing requires oxidativeaccelerators that promote corrosion and thus must be removed by multiplerinsing steps. Conventional inorganic phosphate conversion coatings arealso very brittle and thus can fracture. A seal coat also is typicallyapplied for good corrosion resistance that often includes hexavalentchrome which presents considerable environmental problems.

[0004] It is also generally known that the corrosion resistance of metalsubstrates can be improved by coating the substrate with anautodeposition composition that generally comprise an aqueous solutionof an acid, an oxidizing agent and a dispersed resin. Immersion of ametallic surface in an autodeposition composition produces what is saidto be a self-limiting protective coating on a metal substrate. Thegeneral principles and advantages of autodeposition are explained in amultitude of patents assigned to Parker Amchem and/or Henkel (see, forexample, U.S. Pat. Nos. 4,414,350; 4,994,521; 5,427,863; 5,061,523 and5,500,460).

[0005] U.S. Pat. No. 5,691,048 includes phosphoric acid in a list forpossible acids in an autodepositing composition, but hydrofluoric acidis the preferred acid. This patent also lists hydrogen peroxide, chromicacid, potassium dichromate, nitric acid, sodium nitrate, sodiumpersulfate, ammonium persulfate, sodium perborate and ferric fluoride aspossible oxidizing agents. Hydrogen peroxide and ferric fluoride arepreferred.

[0006] Phosphatizing is also a well-known conversion treatment forproviding corrosion resistance to metal surfaces. U.S. Pat. No.5,011,551 relates to a metal conversion coating composition thatincludes an aliphatic alcohol, phosphoric acid, an alkali nitrate,tannic acid and zinc nitrate. U.S. Pat. No. 4,293,349 relates to a steelsurface protective coating composition that includes pyrogallic acidglucoside, phosphoric acid, phosphates of bivalent transition metalssuch as Zn or Mn, Zn or Mn nitrate, and, optionally, formaldehyde.

[0007] An environmentally acceptable, user-friendly metal treatment withsuperior corrosion resistance and fracture toughness would be verydesirable.

SUMMARY OF THE INVENTION

[0008] According to the present invention there is provided an aqueousmetal surface treatment composition that includes (A) an aqueousdispersion of a phenolic novolak resin that includes water and areaction product of a phenolic resin precursor, a modifying agent and amulti-hydroxy phenolic compound wherein the modifying agent includes atleast one functional moiety that enables the modifying agent to reactwith the plenolic resin precursor and at least one ionic moiety, (B) anacid and, optionally, (C) a flexibilizer. According to one embodimentthe modifying agent is an aromatic compound. According to anotherembodiment the ionic moiety of the modifying agent is sulfate,sulfonate, sulfinate, sulfenate or oxysulfonate and the dispensedphenolic resin reaction product has a carbon/sulfur atom ratio of 20:1to 200:1.

[0009] The metal treatment composition preferably is applied toelectrochemically active metals such as steel. This treatment improvesadhesion of subsequent coatings such as primers and adhesives to themetal surface and it improves corrosion resistance. Since this treatmentrequires only a minimum number of coatings—typically less than three andoften only a single coating—it is much more user friendly thanconventional phosphatizing and eliminates the need for a seal coat. Inaddition, the metal treatment generally does not require any rinsingsteps subsequent to application of the metal treatment composition. Aunique feature of the invention is that the metal treatment compositionis autodepositable.

[0010] It has also been discovered that metal substrates treated withthe compositions of this invention may require sitting at ambientconditions (approximately 25° C.) for an extended time period afterautodepositing and drying (approximately 2 to 24 hours after drying) andprior to application of a subsequent coating of a different composition.This intermediate time period is referred to herein as the “ambientstaging period”. Without this ambient staging period the corrosionresistance of the final product was inconsistent for certain demandingcommercial applications. In addition, formation of a uniformly thickmetal treatment coating is required for superior corrosion resistance.Too thin or too thick a coating also can be detrimental to corrosionprotection.

[0011] Addition of a control agent to autodeposition compositions hasbeen found to dramatically improve uniform coating formation on morecomplex surface topography and enhance the autodeposition ofsubsequently-applied compositions thus improving corrosion resistanceand overall robustness. The protective coating formed by the compositionof the invention is particularly useful for providing corrosionresistance to metal substrates that are subjected to significantstresses and/or strains causing significant flexing or movement of thesubstrate surface. Due to the improved deposition caused by the controlagent, the concentration of active ingredients in an autodepositablecomposition that includes the control agent can be reduced. Anotheradvantage of the invention is that there is no need to post-rinse thetreated surface in order to remove any control agent residue.Furthermore, the control agent eliminates or substantially eliminatesthe ambient staging period thus improving process efficiency.

[0012] Accordingly, a further embodiment of the invention provides anaqueous autodeposition composition that includes an autodepositablecomponent and a control agent, preferably an organic nitro material. Theautodepositable component preferably is an aqueous phenolic resindispersion, particularly the aqueous novolak dispersion mentioned above.The autodeposition composition is particularly useful as a metaltreatment composition that also includes an acid, especially phosphoricacid.

[0013] According to another embodiment of the invention there isprovided a method for treating a metal surface that includes applying tothe surface an aqueous autodeposition composition that includes anautodepositable component and the control agent.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Unless otherwise indicated, description of components in chemicalnomenclature refers to the components at the time of addition to anycombination specified in the description, but does not necessarilypreclude chemical interactions among the components of a mixture oncemixed.

[0015] Certain terms used in this document are defined below.

[0016] “Primer” means a liquid composition applied to a surface as anundercoat beneath a subsequently-applied covercoat. The covercoat can bean adhesive and the primer/adhesive covercoat forms an adhesive systemfor bonding two substrates together.

[0017] “Coating” means a liquid composition applied to a surface to forma protective and/or aesthetically pleasing coating on the surface.

[0018] “Phenolic compound” means a compound that includes it least onehydroxy functional group attached to a carbon atom of an aromatic ring.Illustrative phenolic compounds include unsubstituted phenol per se,substituted phenols such as alkylated phenols and multi-hydroxy phenols,and hydroxy-substituted multi-ring aromatics. Illustrative alkylatedphelnols include methylphonol (also known as eresol), dimethylplhenol(also known as xylenol), 2-ethylphenol, pentylphenol and tert-butylphenol. “Multi-hydroxy phenolic compound” means a compound that includesmore than one hydroxy group on each aromatic ring. Illustrativemulti-hydroxy phenols include 1,3-benzenediol (also known asresorcinol), 1,2-benzenediol (also known as pyrocatechol),1,4-benzenediol (also known as hydroquinone), 1,2,3-benzenetriol (alsoknown as pyrogallol), 1,3,5-benzenetriol and4-tert-butyl-1,2-benzenediol (also known as tert-butyl catechol).Illustrative hydroxy-substituted multi-ring aromatics include4,4′-isopropylidenebisphenol (also known as bisphenol A),4,4′methylidenebisphenol (also known as bisphenol F) and naphthol.

[0019] “Aldehyde compound” means a compound having the generic formulaRCHO. Illustrative aldehyde compounds include formaldehyde,acetaldehyde, propionaldehyde, n-butylaldehyde, n-valeraldehyde,caproaldehyde, heptaldelhyde and other straight-chain aldehydes havingup to 8 carbon atoms, as well as compounds that decompose toformaldehyde such as paraformaldehyde, trioxanie, furfural,hexamethylenetriamine, acetals that liberate formaldehyde on heating,and benzaldehyde.

[0020] “Phenolic resin” generally means the reaction product of aphenolic compound with an aldehyde compound. The molar ratio of thealdehyde compound (for example, formaldehyde) reacted with the phenoliccompound is referred to herein as the “F/P ratio”. The F/P ratio iscalculated on a per hydroxy-substituted aromatic ring basis.

[0021] “Phenolic resin precursor” means an unmodified or conventionalphenolic resin that is reacted with the aromatic modifying agent toproduce the phenolic resin that is dispersed in an aqueous phase.

[0022] “Electrochemically active metals” means iron and all metals andalloys more active than hydrogen in the electromotive series. Examplesof electrochemically active metal surfaces include zinc, iron, aluminumand cold-rolled, polished, pickled, hot-rolled and galvanized steel.

[0023] “Ferrous” means iron and alloys of iron.

[0024] While not wising to be bound to any particular theory, it isbelieved that the metal treatment of this invention is based on theprinciple of autodeposition. When the treatment composition is appliedto an electrochemically active metal the acid reacts with the metal toform multivalent ions (for example, ferric and/or ferrous ions in thecase of steel) that appear to cause the treatment composition to depositon the metal surface a self-limiting, substantially uniform, gelatinous,highly acidic wet film. As the film dries (the drying can be acceleratedby heating) the remaining phosphoric acid converts the surface to therespective metal compound with the respective negative ion of the acid(for example, metal phosphate in the case of phosphoric acid) forming aninterpenetrating network with chelating groups of the aqueous dispersedphenolic novolak resin (A). The coating that is formed when thecomposition is in contact with the metal surface is known as the“unconverted” state. The subsequent drying of the coating converts thecoating to a “converted” state. The formation of the coating issubstantially “self-limiting” in that the coating increases in thicknessand areal density (mass per unit area) the longer the time the metallicsubstrate is immersed in the metal treatment composition. The rate ofthickness and areal density increase, however, decreases rapidly withimmersion time.

[0025] The autodeposition characteristic of the invention is importantto provide corrosion resistance. It allows for the formation of anexceptionally uniform film. Excellent corrosion resistance is possibleonly if the entire surface of a metal part is protected with a barriercoating. This requirement is usually difficult to achieve on substratesurfaces that have very complex topology. With the superiorautodeposition of this invention, wetting and thus protection of suchcomplex surfaces is achieved. A further advantage of the metal treatmentis that it can activate a metal surface for autodeposition of asubsequently applied coating or primer that includes a dispersedphenolic resin as described above. Such a primer is described in moredetail in commonly-owned U.S. Provisional Patent Application 60/072,779titled “Aqueous Primer or Coating”, filed Jan. 27, 1998.

[0026] Another important advantage of the metal treatment composition isthat a bath of the composition does not appear to change in compositionas cumulative metal surfaces are dipped in the bath over a period oftime. It is believed that since the very hydrophilic phenolic resindispersion immobilizes or coagulates on the metal surface as a swollenwet gel rather than as a precipitate, the composition of the bath is thesame as the deposited wet gel and the bath is not depleted. In addition,it appears that there is substantially no build-up of ferrous/ferricions in the bath.

[0027] An important component of the metal treatment composition is theaqueous dispersed phenolic novolak resin (A). This resin is responsiblefor the autodeposition characteristic of the metal treatmentcomposition. The phenolic novolak resin dispersion (A) of the inventivecomposition can be obtained by initially reacting or mixing a phenolicresin precursor and a modifying agent—theoretically via a condensationreaction between the phenolic resin precursor and the modifying agent.It should be recognized that resole resins cannot be used in orformulated into the metal treatment composition due to the presence ofthe acid. Under the acidic conditions of the metal treatment resoles areunstable and can advance quickly to gellation at which point the systemcannot form a film.

[0028] One functional moiety of the modifying agent provides the ionicpendant group that enables stable dispersion of the phenolic resin.Without the ionic pendant group, the phenolic resin would be unable tomaintain a stable dispersion in water. Since the ionic pendant groupprovides for the stability of the dispersion there is no need, or at themost a minimal need, for surfactants. The presence of surfactants in anaqueous composition is a well-known hindrance to the composition'sperformance.

[0029] The other important functional moiety in the modifying agentenables the modifying agent to react with the phenolic resin precursor.The modifying agent can contain more than one ionic pendant group andmore than one reaction-enabling moiety.

[0030] Incorporation of aromatic sulfonate functional moieties into thephenolic resin structure via condensation is the preferred method ofproviding the ionic pendant groups. Accordingly, one class of ionicmoieties are substituents on an aromatic ring that include a sulfur atomcovalently or ionically bonded to a carbon atom of the aromatic ring.Examples of covalently bound sulfur-containing substituents aresulfonate (—OS(O)₂O³¹ M⁻), sulfinate (—S(O)O⁻M⁺), sulfenate (—SO⁻M⁺) andoxysulfonate (—OS(O)₂O⁻M⁺), wherein M can be any monovalent ion such asNa, Li, K, or NR¹ ₃ (wherein R¹ is hydrogen or an alkyl). Anotherexample of a covalently bound substituent is sulfate ion. Sulfonate isthe preferred ionic group. The modifying agent should not include orintroduce any multivalent ions into the phenolic resin dispersion sinceit is expected that the presence of multivalent ions would cause thephenolic resin to precipitate rather than remain dispersed.

[0031] The reaction-enabling functional moiety of the modifying agentcan be any functional group that provides a site on the modifying agentfor undergoing condensation with a phenolic resin. If the phenolic resinprecursor is a resole, the modifying agent reacts with an alkylol orbenzyl ether group of the resole. If the modifying agent is aromatic,the reaction-enabling functional moiety is a substituent on the aromaticring that causes a site on the ring to be reactcive to the alkylol orbenzyl ether of the resole precursor. An example of such a substituentis a hydlroxy or hydroxyalkyl, with hydroxy being preferred. Thehydroxy- or hydroxyalkyl-substituted aromatic modifying agent isreactive at a site ortho and/or para to each hydroxy or hydroxyalkylsubstituent. In other words, the aromatic modifying agent is bonded to,or incorporated into, the phenolic resin precursor at sites on thearomatic ring of the modifying agent that are ortho and/or para to ahydroxy or hydroxyalkyl substituent. At least two reaction-enablingfunctional moieties are preferred to enhance the reactivity of thearomatic modifying agent with the phenolic resin precursor.

[0032] Alternatively, the reaction-enabling functional moiety of themodifying agent can be a formyl group (—CHO), preferably attached to acarbon atom of an aromatic ring. In this instance, the phenolic resinprecursor is a novolak rather than a resole. The novolak precursor isreacted via an acid catalyzed aldehyde condensation reaction with theformyl group-containing modifying agent so that the formyl group forms adivalent methylene linkage to an active site on an aromatic ring of thebackbone structure of the novolak precursor. Consequently, the modifyingagent structure (including the ionic moiety) is incorporated into thephenolic structure through the generated methylene linkage. Examples ofsuch formyl group-containing modifying agents include 2-formylbenzenesulfonate, 5-formylfuran sulfonate and (R)(SO₃)CH—CH₂—C(O)(H) compoundswherein R is C₁-C₄ alkyl groups.

[0033] Another alternative reaction-enabling functional moiety could bea diazo group (—N₂ ⁺), preferably attached to a carbon atom of anaromatic ring. In this instance, the phenolic resin precursor is anovolak rather than a resole. The novolak precursor is reacted via adiazo coupling reaction with the diazo group-containing modifying agentso that the diazo group forms a divalent diazo linkage (—N═) to anactive site on an aromatic ring of the backbone structure of the novolakprecursor. Consequently, the modifying agent structure (including theionic moiety) is incorporated into the phenolic structure through thediazo linkage. An example of such diazo modifying agents is1-diazo-2-naphthol-4-sulfonic acid.

[0034] The modifying agent also can optionally include a functionalmoiety that is capable of chelating with a metal ion that is present ona substrate surface on which the phenolic resin dispersion is applied.The chelating group remains as a residual group after the condensationof the phenolic resin precursor and the aromatic modifying agent.Typically, the chelating group is a substituent on the aromatic ringthat is capable of forming a 5- or 6-membered chelation structure with ametal ion. Examples of such substituents include hydroxy andhydroxyalkyl, with hydroxy being preferred. At least two such functionalgroups must be present on the modifying agent molecule to provide thechelating. In the case of an aromatic modifying agent, the chelatinggroups should be located in an ortho position relative to each other. Asignificant advantage of the invention is that hydroxy or hydroxyalkylsubstituents on the aromatic modifying agent can serve tworoles—condensation enablement and subsequent metal chelating.

[0035] An aromatic modifying agent is particularly advantageous.Preferably, the ionic group and the reaction-enabling moiety are notsubstituents on the same aromatic ring. The ionic group, particularlysulfonate, appears to have a strong deactivating effect on condensationreactions of the ring to which it is attached. Consequently, an ionicgroup attached to the same ring as the reaction-enabling moiety wouldnot allow the modifying agent to readily react with the phenolic resin.However, it should be recognized that this consideration for thelocation of the ionic and reaction-enabling moieties is not applicableto the formyl group-containing modifying agent and diazo modifyingagent.

[0036] A preferred structure for the aromatic modifying agent isrepresented by formulae Ia or Ib below:

[0037] wherein X is the ionic group; Y is the reaction-enablingsubstituent; Z is the chelating substituent; L¹ is a divalent linkinggroup such as an alkylence radical (for example, methylene) or a diazo(—N═N—); a is 1; b is 1 to 4; m is 0 or 1; and c and d are eachindependently 0 to 3, provided there are not more than 4 substituents oneach aromatic ring. If a chelating group Z is present it is positionedortho to another chelating group Z or to Y. It should be recognized thatthe reaction-enabling substituent Y may also act as a chelatingsubstituent. In this instance, the aromatic modifying agent may notinclude an independent chelating substituent Z. An aromatic modifyingagent according to formulae Ia or Ib could also include othersubstituents provided they do not adversely interfere with the ionicgroup or the condensation reaction.

[0038] Illustrative aromatic modifying agents include salts of6,7-dihydroxy-2-napthalenesulfonate;6,7-dihydroxy-1-naphthalenesulfonate;6,7-dihydroxy-4-naphthalenesulfonate; Acid Red 88; Acid Alizarin VioletN; Erichrome Black T; Erichrome Blue Black B; Brilliant Yellow; CroceinOrange G; Biebrich Yellow; and Palatine Chrome Black 6BN.6,7-dihydroxy-2-naphthalenesulfonate, sodium salt is the preferredaromatic modifying agent.

[0039] It should be recognized that the preferred sulfonate modificationcontemplated herein involves an indirect sulfonation mechanism. In otherwords, the aromatic modifying agent includes a sulfonate group and isreacted with another aromatic compound (the phenolic resin precursor) toobtain the chain extended, sulfonate-modified phenolic resin product.This indirect sulfonation is distinctly different than directsulfonation of the phenolic resin precursor.

[0040] Any phenolic resin could be employed as the phenolic resinprecursor, but it has been found that resoles are especially suitable.The resole precursor should have a sufficient amount of active alkylolor benzyl ether groups that can initially condense with the modifyingagent and then undergo further subsequent condensation. Of course, thephenolic resin precursor has a lower molecular weight than the finaldispersed resin since the precursor undergoes condensation to make thefinal dispersed resin. Resoles are prepared by reacting a phenoliccompound with an excess of an aldehyde in the presence of a basecatalyst. Resole resins are usually supplied and used as reactionproduct mixtures of monomeric phenolic compounds and higher molecularweight condensation products having alkylol (—ArCH₂—OH) or benzyl ethertermination (—ArCH₂—O—CH₂Ar), wherein Ar is an aryl group. These resolemixtures or prepolymers (also known as stage A resin) can be transformedinto three-dimensional, crossliniked, insoluble and infusible polymersby the application of heat.

[0041] The reactants, conditions and catalysts for preparing resolessuitable for the resole precursor of the present invention arewell-known. The phenolic compound can be any of those previously listedor other similar compounds, although multi-hydroxy phenolic compoundsare undesirable. Particularly preferred phenolic compounds for makingthe resole precursor include phenol per se and alkylated phenol. Thealdehyde also can be any of those previously listed or other similarcompounds, with formaldehyde being preferred. Low molecular weight,water soluble or partially water soluble resoles are preferred as theprecursor because such resoles maximize the ability to condense with themodifying agent. The F/P ratio of the resole precursor should be atleast 0.90. Illustrative commercially available resoles that aresuitable for use as a precursor include a partially water soluble resoleavailable from Georgia Pacific under the trade designation BRL2741 and apartially water soluble resoles available from Schenectady Internationalunder the trade designations HRJ11722 and SG3100.

[0042] Preferably, the dispersed novolak is produced by reacting ormixing 1 mol of modifying agent(s) with 2-20 mol of phenolic resin(preferably resole) precursor(s) and, preferably, 2-20 mol ofmulti-hydroxy phenolic compound(s). An aldehyde compound, preferablyformaldehyde, is also required to make the novolak. The aldehydecompound can optionally be added as a separate ingredient in the initialreaction mixture or the aldehyde compound can be generated in situ fromthe resole precursor. The resole precursor(s), multi-hydroxy phenoliccompound(s) and modifying agent(s) co-condense to form the dispersednovolak. The reaction typically is acid catalyzed with an acid such asphosphoric acid. The F/P ratio of aldelyde compound(s) to combinedamount of resole precursor(s) and multi-hydroxy phenolic compound(s) inthe initial reaction mixture preferably is less than 0.9. Preferably,synthesis of the dispersed novolak is a two stage reaction. In the firststage, the resole precursor(s) is reacted with the modifying agent(s)and, optionally, a small amount of multi-hydroxy phenolic compound(s).Once this first stage reaction has reached the desired point (i.e. theresin can be readily formed into a translucent dispersion), the acidcatalyst and a greater amount of multi-hydroxy phenolic compound(s) isadded to the reaction mixture. Pyrocatechol (also simply known ascatechol) is a preferred multi-hydroxy phenolic compound for reacting inthe first stage and resorcinol is a preferred multi-hydroxy phenoliccompound for reacting in the second stage.

[0043] Hydrophilic novolaks typically have a hydroxy equivalents ofbetween 1 and 3 per aromatic ring. Preferably, dispersed hydrophilicnovolaks according to the invention have a hydroxy equivalents of 1.1 to2.5, more preferably 1.1 to 2.0. The hydroxy equivalents is calculatedbased on the amount of multi-hydroxy phenolic compounds used to make thenovolak.

[0044] According to a preferred embodiment, the dispersed phenolic resinreaction product contains a mixture of oligomers having structuresbelieved to be represented by the following formulae IIa or IIb:

[0045] wherein X, Y, Z and L¹ and subscripts a, b, c, d and m are thesame as in formulae Ia and Ib, e is 1 to 6, L² is a divalent linkinggroup and Ph is the phenolic resin backbone structure, provided the—(L²—Ph) group(s) is(are) ortho or para to a Y group. L² depends uponthe particular phenolic resin, but typically is a divailent alkyleneradical such as methylene (—CH₂—) or oxydimethylene (—CH₂—O—CH₂—).Preferably, e is 2 and the —(L²—Ph) groups are in para position to eachother.

[0046] According to a preferred embodiment wherein the phenolic resin isa novolak and the modifying agent is a naphthalene having a ionicpendant group X and two reaction-enabling substituents Y, the dispersedphenolic resin reaction product contains a mixture of oligomers havingstructures believed to be represented by the following formula IV:

[0047] wherein X and Y are the same as in formulae Ia and Ib, a is 0 or1, n is 0 to 5 and R⁴ is independently hydroxyl, alkyl, aryl, alkylarylor aryl ether. Preferably, R⁴ is tert-butyl. If6,7-dihydroxy-2-naphthalenesulfonate, sodium salt is the modifyingagent, X will be SO₃ ⁻ Na⁺ and each Y will be OH. In this case thehydroxy groups for Y will also act as chelating groups with a metal ion.

[0048] It should be recognized that the dispersed phenolic resinreaction product may also contain oligomers or compounds havingstructures that vary from the idealized structures shown in formula IV.

[0049] If the modifying agent includes a sulfur-containing ionic group,the resulting modified phenolic resin should have a carbon/sulfur atomratio of 20:1 to 200:1, preferably 20:1 to 100:1. If the sulfur contentis greater than the 20:1 carbon/sulfur atom ratio, the modified phenolicresin begins to become water soluble, is more stable with respect tomultivalent ions and is difficult to thermoset. These characteristicsare adverse to the preferred use of the phenolic resin dispersion of theinvention. If the sulfur content is below the 200:1 carbon/sulfur atomratio, then the resin dispersion cannot maintain its stability. Viewedanother way, the dispersed phenolic resins have 0.01 to 0.10, preferably0.03 to 0.06, equivalents of sulfolnate functionality/100 g resin. Theaqueous dispersion of the phenolic resin preferably has a solids contentof 1 to 50, preferably 15 to 30.

[0050] The modifying agent and the phenolic resin precursor can bereacted under conditions effective to promote condensation of themodifying agent with the phenolic resin precursor. The reaction iscarried out in water under standard phenolic resin condensationtechniques and conditions. The reactant mixture (including water)generally is heated from 50 to 100° C. under ambient pressure, althoughthe specific temperature may differ considerably depending upon thespecific reactants and the desired reaction product. The resultingproduct is a concentrate that is self-dispersible upon the addition ofwater and agitation to reach a desired solids content. The finaldispersion can be filtered to remove any gelled agglomerations.

[0051] The intermediate modified resoles or novolaks that are initiallyproduced in the synthesis are not necessarily water dispersible, but asthe chain extension is advanced the resulting chain extended modifiedresoles or novolaks become progressively more water dispersible bysimple mechanical agitation. The chain extension for the dispersedresole is determined by measuring the viscosity of the reaction mixture.Once the resole reaction mixture has a reached the desired viscosity,which varies depending upon the reactant composition, the reaction isstopped by removing the heat. The chain extension for the dispersednovolak is determined by pre-selecting the F/P ratio of the totalreaction mixture (in other words, the amount of aldehyde compound(s)relative to the amount of phenolic(s) in both the first and secondstages). The reaction for the novolak is allowed to proceed untilsubstantially all the total amount of the reactants have reacted. Inother words, there is essentially no unreacted reactant remaining.Preferably, the molecular weight (i.e., chain extension) of the novolakshould be advanced to just below the gel point.

[0052] The novolak dispersion can be present in the metal treatmentcomposition in any amount. Preferably, it is present in an amount of 1to 20, more preferably, 2 to 6, based on the total weight of thenon-volatile components of the composition.

[0053] The phenolic resin dispersion forms environmentally (especiallycorrosion) resistant, non-resolvatable films when applied to a metalsurface and cured. As used herein, “non-resolvatable” means that thefilm does not resolvate when in aqueous covercoat is applied to the filmbefore it is thermoset. If the film resolvated, the components of thefilm would dissolve or disperse into the aqueous covercoat thusdestroying any advantage intended from the formation of the film on asurface. The low ionic content of the modified phenolic resin dispersion(relative to water soluble phenolic resins) allows them to behavesimilarly to non-ionically modified resins and form very water resistantfilms on curing.

[0054] The acid can be any acid that is capable of reacting with a metalto generate multivalent ions. Illustrative acids include hydrofluoricacid, phosphoric acid, sulfuric acid, hydrochloric acid and nitric acid.In the case of steel the multivalent ions will be ferric and/or ferrousions. Aqueous solutions of phosphoric acid are preferred. When the acidis mixed into the composition presumably the respective ions are formedand exist as independent species in addition to the presence of the freeacid. In other words, in the case of phosphoric acid, phosphate ions andfree phosphoric acid co-exist in the formulated final multi-componentcomposition. The acid preferably is present in an amount of 5 to 300parts by weight, more preferably 10 to 160 parts by weight, based on 100parts by weight of the phenolic novolak resin dispersion (A).

[0055] Water, preferably deionized water, is utilized in the metaltreatment composition of the invention in order to vary the solidscontent. Although the solids content may be varied as desired, thesolids content of the metal treatment composition typically is 1 to 10,preferably 3 to 6%. Since the metal treatment composition is waterborneit is substantially free of volatile organic compounds.

[0056] The resulting coating from application of the metal treatmentcomposition is a thin, tightly bound interpenetrating organic/inorganicmatrix of phenolic/metal phosphates at the metal substrate interface.This matrix can be further flexibilized with polymers. The flexibilizer(C) is any material that contributes flexibility and/or toughness to thefilm formed from the composition. The toughness provided by theflexibilizer provides fracture resistance to the film. The flexibilizershould be non-glassy at ambient temperature and be an aqueous emulsionlatex or aqueous dispersion that is compatible with the phenolic novolakresin dispersion (A). The flexibilizer preferably is formulated into thecomposition in the form of an aqueous emulsion latex or aqueousdispersion

[0057] Suitable flexibilizers include aqueous latices, emulsions ordispersions of (poly)butadiene, neoprene, styrene-butadiene rubber,acrylonitrile-butadiene rubber (also known as nitrile rubber),halogenated polyolefin, acrylic polymer, urethane polymer,ethylene-propylene copolymer rubber, ethylene-propylene-diene terpolymerrubber, styrene-acrylic copolymer, polyamide, poly(viniyl acetate) andthe like. Halogenated polyolefins, nitrile rubbers and styrene-acryliccopolymers are preferred.

[0058] A suitable styrene-acrylic polymer latex is commerciallyavailable from Goodyear Tire & Rubber under the trade designationPLIOTEC and described, for example, in U.S. Pat. Nos. 4,968,741;5,122,566 and 5,616,635. According to U.S. Pat. No. 5,616,635, such acopolymer latex is made from 45-85 weight percent vinyl aromaticmonomers, 15-50 weight percent of at least one alkyl acrylate monomerand 1-6 weight percent unsaturated carbonyl compound. Styrene is thepreferred vinyl aromatic monomer, butyl acrylate is the preferredacrylate monomer and acrylic acid and methacrylic acid are the preferredunsaturated carbonyl compound. The mixture for making the latex alsoincludes at least one phosphate ester surfactant, at least onewater-insoluble nonionic surface active agent and at least one freeradical initiator.

[0059] If nitrile rubber is the flexibilizer, it is preferably mixedinto the composition as an emulsion latex. It is known in the art thatnitrile rubber emulsion latices are generally made from at least onemonomer of acrylonitrile or an alkyl derivative thereof and at least onemonomer of a conjugated diene, preferably butadiene. According to U.S.Pat. No. 4,920,176 the acrylonitrile or alkyl derivative monomer shouldbe present in an amount of 0 or 1 to 50 percent by weight based on thetotal weight of the monomers. The conjugated diene monomer should bepresent in an amount of 50 percent to 99 percent by weight based on thetotal weight of the monomers. The nitrile rubbers can also optionallyinclude various co-monomers such as acrylic acid or various estersthereof, dicarboxylic acids or combinations thereof. The polymerizationof the monomers typically is initiated via free radical catalysts.Anionic surfactants typically are also added. A suitable nitrile rubberlatex is available from B. F. Goodrich under the trade designationHYCAR.

[0060] Representative halogenated polyolefins include chlorinatednatural rubber, chlorine- and bromine-containing synthetic rubbersincluding polychloroprene, chlorinated polychloroprene, chlorinatedpolybutadiene, hexachloropentadiene, butadiene/halogenated cyclicconjugated diene adducts, chlorinated bultadiene styrene copolymers,chlorinated ethylene propylene copolymers andethylene/propylene/non-conjugated diene terpolymers, chlorinatedpolyethylene, chlorosulfonated polyethylene,poly(2,3-dichloro-1,3-butadiene), brominatedpoly(2,3-dichloro-1,3-butadiene), copolymers of α-haloacrylonitriles and2,3-dichloro-1,3-butadiene, chlorinated poly(vinyl chloride) and thelike including mixtures of such halogen-containing elastomers.

[0061] Latices of the halogenated polyolefin can be prepared accordingto methods known in the art such as by dissolving the halogenatedpolyolefin in a solvent and adding a surfactant to the resultingsolution. Water can then be added to the solution under high shear toemulsify the polymer. The solvent is then stripped to obtain a latex.The latex can also be prepared by emulsion polymerization of thehalogenated ethylenically unsaturated monomers.

[0062] Butadiene latices are particularly preferred as the flexibilizer(C). Methods for making butadiene latices are well-known and aredescribed, for example, in U.S. Pat. Nos. 4,054,547 and 3,920,600, bothincorporated herein by reference. In addition, U.S. Pat. Nos. 5,200,459;5,300,555; and 5,496,884 disclose emulsion polymerization of butadienemonomers in the presence of polyvinyl alcohol and a co-solvent such asan organic alcohol or a glycol.

[0063] The butadiene monomers useful for preparing the butadiene polymerlatex can essentially be any monomer containing conjugated unsaturation.Typical monomers include 2,3-dichloro-1,3-butadiene; 1,3-butadiene;2,3-dibromo-1,3-butadiene isoprene; isoprene; 2,3-dimethylbutadiene;chloroprene; bromoprene; 2,3-dibromo-1,3-butadiene;1,1,2-trichlorobutadiene; cyanoprene; hexachlorobutadiene; andcombinations thereof. It is particularly preferred to use2,3-dichloro-1,3-butadiene since a polymer that contains as its majorportion 2,3-dichloro-1,3-butadiene monomer units has been found to beparticularly useful in adhesive applications due to the excellentbonding ability and barrier properties of the2,3-dichloro-1,3-butadiene-based polymeres. As described above, anespecially preferred embodiment of the present invention is one whereinthe butadiene polymer includes at least 60 weight percent, preferably atleast 70 weight percent, 2,3-dichloro-1,3-butadiene monomer units.

[0064] The butadiene monomer can be copolymerized with other monomers.Such copolymerizable monomers include α-haloacrylonitriles such asα-bromoacrylonitrile and α-chloroacrylonitrile; αβ-unsaturatedcarboxylic acids such as acrylic, methacrylic, 2-ethylacrylic,2-propylacrylic, 2-butylacrylic and itaconic acids;alkyl-2-haloacrylates such as ethyl-2-chloroacrylate andethyl-2-bromoacrylate; α-bromovinylketone; vinylidene chloride; vinyltoluenes; vinylnaphthalenes; vinyl ethers, esters and ketones such asmethyl vinyl ether, vinyl acetate and methyl vinyl ketone; estersamides, and nitriles of acrylic and methacrylic acids such as ethylacrylate, methyl methacrylate, glycidyl acrylate, methacrylamide andacrylonitrile; and combinations of such monomers. The copolymerizablemonomers, if utilized, are preferably α-haloacrylonitrile and/orα,β-unsaturated carboxylic acids. The copolymerizable monomers may beutilized in an amount of 0.1 to 30 weight percent, based on the weightof the total monomers utilized to form the butadiene polymer.

[0065] In carrying out the emulsion polymerization to produce the latexother optional ingredients may be employed during the polymerizationprocess. For example, conventional anionic and/or nonionic surfactantsmay be utilized in order to aid in the formation of the latex. Typicalanionic surfactants include carboxylates such as fatty acid soaps fromlauric, stearic, and oleic acid; aryl derivatives of sarcosine such asmethyl glycine; sulfates such as sodium lauryl sulfate; sulfated naturaloils and esters such as Turkey Red Oil; alkyl aryl polyether sulfates;alkali alkyl sulfates; ethoxylated aryl sulfonic acid salts; alkyl arylpolyether sulfonates; isopropyl naphthalene sulfonates; sulfosuccinates;phosphate esters such as short chain fatty alcohol partial esters ofcomplex phosphates; and orthophosphate esters of polyethoxylated fattyalcohols. Typical nonionic surfactants include ethoxylated (ethyleneoxide) derivatives such as ethoxylated alkyl aryl derivatives; mono- andpolyhydric alcohols; ethylene oxide/propylene oxide block copolymers;esters such as glyceryl monostearate; products of the dehydration ofsorbitol such as sorbitan monostearate and polyethylene oxide sorbitanmonolaurate; amines; lauric acid; and isopropenyl halide. A conventionalsurfactant, if utilized, is employed in an amount of 0.01 to 5 parts,preferably 0.1 to 2 parts, per 100 parts by weight of total monomersutilized to form the butadiene polymer.

[0066] In the case of dichlorobutadiene homopolymers, anionicsurfactants are particularly useful. Such anionic surfactants includealkyl sulfonates and alkyl aryl sulfonates (commercially available fromStepan under the trade designation POLYSTEP) and sulfonic acids or saltsof alkylated diphenyl oxide (for example, didodecyl diphenyleneoxidedisulfonate or dihexyl diphenyloxide disulfonate commercially availablefrom Dow Chemical Co. under the trade designation DOWFAX).

[0067] Chain transfer agents may also be employed during emulsionpolymerization in order to control the molecular weight of the butadienepolymer and to modify the physical properties of the resultant polymeras is known in the art. Any of the conventional organicsulfur-containing chain transfer agents may be utilized such as alkylmercaptans and dialkyl xanthogen disulfides.

[0068] The emulsion polymerization is typically triggered by a freeradical initiator. Illustrative free radical initiators includeconventional redox systems, peroxide systems, azo derivatives andhydroperoxide systems. The use of a redox system is preferred andexamples of such systems include ammonium persulfate/sodiummetabisulfite, ferric sulfate/ascorbic acid/hydroperoxide andtributylborane/hydroperoxide, with ammonium persulfate/sodiummetabisulfite being most preferred.

[0069] The emulsion polymerization is typically carried out at atemperature of 10°-90° C., preferably 40°-60° C. Monomer conversionusually ranges from 70-100, preferably 80-100, percent. The laticespreferably have a solids content of 10 to 70, more preferably 30 to 60,percent; a viscosity between 50 and 10,000 centipoise at 25° C.; and aparticle size between 60 and 300 nanometers.

[0070] Especially preferred as the butadiene latex is a butadienepolymer that has been emulsion polymerized in the presence of a styrenesulfonic acid, stylene sulfonate, poly(styrene sulfonic acid), orpoly(styrene sulfonate) stabilizer to form the latex. Poly(styrenesulfonate) is the preferred stabilizer. This stabilization system isparticularly effective for a butadiene polymer that is derived from atleast 60 weight percent dichlorobutadiene monomer, based on the amountof total monomers used to form the butadiene polymer. The butadienepolymer latex can be made by known emulsion polymerization techniquesthat involve polymerizing the butadiene monomer (and copolymerizablemonomer, if present) in the presence of water and the styrlene sulfonicacid, styrene sulfonate, poly(styrene sulfon acid), or poly(styrenesulfonate) stabilizer. The sulfonates can be salts of any cationicgroups such as sodium, potassium or quaternary ammonium. Sodium styrenesulfonate is a preferred styrene sulfonate compound. Poly(styrenesulfonate) polymers include poly(styrene sulfonate) homopolymer andpoly(styrene sulfonate) copolymers such as those with maleic anhydride.Sodium salts of poly(styrene sulfonate) are particularly preferred andare commercially available from National Starch under the tradedesignation VERSA TL. The poly(styrene sulfonate) can have a weightaverage molecular weight from 5×10⁴ to 1.5×10^(6,) with 1.5×10⁵ to2.5×10⁵ being preferred. In the case of a poly(styrene sulfonate) orpoly(styrene sulfonic acid) it is important to recognize that theemulsion polymerization takes place in the presence of the pre-formedpolymer. In other words, the butadiene monomer is contacted with thepre-formed poly(styrene sulfonate) or poly(styrene sulfonic acid). Thestabilizer preferably is present in an amount of 0.1 to 10 parts,preferably 1 to 5 parts, per 100 parts by weight of total monomersutilized to form the butadiene polymer.

[0071] The flexibilizer (C), if present, preferably is included in thecomposition in an amount of 5 parts by weight to 300 parts by weight,based on 100 parts by weight phenolic novolak resin dispersion (A). Morepreferably, the flexibilizer is present in an amount of 25 parts byweight to 100 parts by weight, based on 100 parts by weight of thephenolic novolak resin dispersion (A).

[0072] The modified phenolic resin dispersion can be cured to form ahighly crosslinked thermoset via known curing methods for phenolicresins. The curing mechanism can vary depending upon the use and form ofthe phenolic resin dispersion. For example, curing of the dispersedresole embodiment typically can be accomplished by subjecting thephenolic resin dispersion to heat. Curing of the dispersed novolakembodiment typically can be accomplished by addition of an aldehydedonor compound.

[0073] Since the dispersed phenolic resin (A) is a novolak, a curativeshould be introduced in order to cure the film formed by the metaltreatment composition. It should be noted that the metal treatmentcomposition cannot itself include a phenolic resin curative thesecuratives are not storage stable under acidic conditions. Curing of thefilm can be accomplished by the application of a curative-containingtopcoat over the metal treatment film. Typically, the metal treatmentcomposition is applied to a metal surface (either conventionally or viaautodeposition) and then dried. The curative-containing topcoat then isapplied to the thus treated metal surface. The curative contained in thetopcoat can be an aldehlyde donor compound or an aromatic nitrosocompound. Topcoat compositions that include either one or both of thesecuratives are well-known and commercially available.

[0074] The aldehyde donor can be essentially be any type of aldehydeknown to react with hydroxy aromatic compounds to form cured orcrosslinked novolak phenolic resins. Typical compounds useful as analdehyde (e.g., formaldehyde) source in the present invention includeformaldehyde and aqueous solutions of formaldehyde, such as formalin;acetaldehyde; propionaldehyde; isobutyraldehyde; 2-ethylhexadehyde;2-methylpentaldehyde; 2-ethylhexaldehyde; benzaldehyde; as well ascompounds which decompose to formaldehyde, such as paraformaldehyde,trioxane, furfural, hexamethylenetetramine, anhydromaldehydeaniline,ethylene diamine formaldehyde; acetals which liberate formaldehyde onheating; methylol derivatives of urea and formaldehyde; methylolphenolic compounds; and the like.

[0075] It has been found that when the metal treatment composition isused in combination with the primer described in U.S. Provisional PatentApplication No. 60/072,779 (incorporated herein by reference),formaldehyde species generated from the resole present in the primerappear to co-cure the novolak in the metal treatment coating viadiffusion. In addition, curing or crosslinking of the novolak may occurthrough ionic crosslinking and chelation with the metal ions generatedby the acid-metal substrate reaction.

[0076] Additionally, high molecular weight aldehyde homopolymers andcopolymers can be employed as a latent formaldehyde source in thepractice of the present invention. A latent formaldehyde source hereinrefers to a formaldehyde source which will release formaldehyde only inthe presence of heat such as the heat applied during the curing of anadhesive system. Typical high molecular weight aldehyde homopolymers andcopolymers include (1) acetal homopolymers, (2) acetal copolymers, (3)gamma-polyoxy-methylene ethers having the characteristic structure:

R₁₀O—(CH₂O)_(n)—R₁₁

[0077] and (4) polyoxymethylene glycols having the characteristicstructure:

HO—(R₁₂O)_(x)—(CH₂O)_(n)—(R₁₃O)_(x)—H

[0078] wherein R₁₀ and R₁₁ can be the same or different and each is analkyl group having from about 1 to 8, preferably 1 to 4, carbon atoms,R₁₂ and R₁₃ can be the same or different and each is an alkylene grouphaving from 2 to 12, preferably 2 to 8, carbon atoms; n is greater than100, and is preferably in the range from about 200 to about 2000; and xis in the range from about 0 to 8, preferably 1 to 4, with at least onex being equal to at least 1. The high molecular weight aldehydehomopolymers and copolymers are further characterized by a melting pointof at least 75° C., i.e. they are substantially inert with respect tothe phenolic system until heat activated; and by being substantiallycompletely insoluble in water at a temperature below the melting point.The acetal homopolymers and acetal copolymers are well-known articles ofcommerce. The polyoxymethylene materials are also well known and can bereadily synthesized by the reaction of monoalcohols having from 1 to 8carbon atoms or dihydroxy glycols and ether glycols withpolyoxymethylene glycols in the presence of an acidic catalyst. Arepresentative method of preparing these crosslinking agents isdescribed in U.S. Pat. No. 2,512,950, which is incorporated herein byreference. Gamma-polyoxymethylene ethers are generally preferred sourcesof latent formaldehyde and a particularly preferred latent formaldehydesource for use in the practice of the invention is 2-polyoxymethylenedimethyl ether.

[0079] The aromatic nitroso compound can be any aromatic hydrocarbon,such as benzenes, naphthalenes, anthracenes, biphenyls, and the like,containing at least two nitroso groups attached directly to non-adjacentring carbon atoms. Such aromatic nitroso compounds are described, forexample, in U.S. Pat. No. 3,258,388; U.S. Pat. No. 4,119,587 and U.S.Pat. No. 5,496,884.

[0080] More particularly, such nitroso compounds are described asaromatic compounds having from 1 to 3 aromatic nuclei, including fusedaromatic nuclei, having from 2 to 6 nitroso groups attached directly tonon-adjacent nuclear carbon atoms. The preferred nitroso compounds arethe dinitroso aromatic compounds, especially the dinitrosobenzenes anddinitrosonaphthalenes, such as the meta- or para-dinitrosobenzenes andthe meta- or para-dinitrosonaphthalenes. The nuclear hydrogen atoms ofthe aromatic nucleus can be replaced by alkyl, alkoxy, cycloalkyl, aryl,aralkyl, alkaryl, arylamine, arylnitroso, amino, halogen and similargroups. Thus, where reference is made herein to “aromatic nitrosocompound” it will be understood to include both substituted andunsubstituted nitroso compounds.

[0081] Particularly preferred nitroso compounds are characterized by theformula:

(R)_(m—Ar—(NO)) ₂

[0082] wherein Ar is selected from the group consisting of phenylene andnaphthalene; R is a monovalent organic radical selected from the groupconsisting of alkyl, cycloalkyl, aryl, aralkyl, alkaryl, arylamine andalkoxy radicals having from 1 to 20 carbon atoms, amino, or halogen, andis preferably an alkyl group having from 1 to 8 carbon atoms; and m is0; 1, 2, 3, or 4, and preferably is 0.

[0083] Exemplary suitable aromatic nitroso compounds includem-dinitrosobenzene, p-dinitrosobenzene, m-dinitrosonaphthalene,p-dinitrosonaphthalene, 2,5-dinitroso-p-cymene,2-methyl-1,4-dinitrosobenzene, 2-methyl-5-chloro-1,4- dinitrosobenzene,2-fluro-1,4-dinitrosobenzene, 2-methoxy- 1-3-dinitrosobenzene,5-chloro-1,3-dinitrosobenzene, 2-benzyl-1,4-dinitrosobenzene,2-cyclohexyl-1,4-dinitrosobenzene and combinations thereof. Particularlypreferred are m-dinitrosobenzene and p-dinitrosobenzene.

[0084] The aromatic nitroso compound precursor may be essentially anycompound that is capable of being converted, typically by oxidation, toa nitroso compound at elevated temperatures, typically from about140-200° C. The most common aromatic nitroso compound precursors arederivatives of quinone compounds. Examples of such quinone compoundderivatives include quinone dioxime, dibenzoquinone dioxime,1,2,4,5-tetrachlorobenzoquinone, 2-methyl-1,4-benzoquinone dioxime,1,4-naphthoquinone dioxime, 1,2-naphthoquinone dioxime and2,6-naphthoquinone dioxime.

[0085] The control agent mentioned above is especially useful in themetal treatment composition of the invention described above but itcould also be useful in any multi-component composition that includes anautodepositable component. The autodepositable component is any materialthat enables (either by itself or in combination with the othercomponents of the composition) the multi-component composition toautodeposit on a metal surface. Preferably, the autodepositablecomponent is any water-dispersible or water soluble resin that iscapable of providing autodeposition ability to the composition. Suchresins include those derived from ethylenically unsaturated monomerssuch as polyvinylidene chloride, polyvinyl chloride, polyethylene,acrylic, acrylonitrile, polyvinyl acetate and styrene-butadiene (seeU.S. Pat. Nos. 4,414,350; 4,994,521; and 5,427,863; and PCT PublishedPatent Application No. WO 93/15154). Urethane and polyester resins arealso mentioned as being useful. Certain epoxy and epoxy-acrylate resinsare also said to be useful autodeposition resins (see U.S. Pat. No.5,500,460 and PCT Published Patent Application No. WO 97/07163). Blendsof these resins may also be used.

[0086] Especially suitable autodepositable resins are aqueous phenolicresin dispersions described in co-pending, commonly assigned U.S.Provisional Patent Application No. 60/072887, incorporated herein byreference. The novolak version of this dispersed resin is describedabove in connection with the metal treatment composition. There is alsoa resole version with which the control agent of the invention may beformulated into a multi-component composition.

[0087] The phenolic resin precursor and modifying agent used to make thedispersed resole are the same as those described for the dispersednovolak. However, the dispersed resole is produced by the reaction of 1mol of modifying agent(s) with 1 to 20 mol of phenolic resinprecursor(s). A dispersed resole typically can be obtained by reacting aresole precursor or a mixture of resole precursors with the modifyingagent or a mixture of agents without any other reactants, additives orcatalysts. However, other reactants, additives or catalysts can be usedas desired. Multi-hydroxy phenolic compound(s) can optionally beincluded in relatively small amounts in the reactant mixture for theresole. Synthesis of the resole does not require an acid catalyst.

[0088] Hydrophilic resoles typically have a F/P ratio of at least 1.0.According to the invention, hydrophilic resoles having a F/P ratio muchgreater than 1.0 can be successfully dispersed. For example, it ispossible to make an aqueous dispersion of hydrophilic resoles having aF/P ratio of at least 2 and approaching 3, which is the theoretical F/Pratio limit.

[0089] According to a particularly preferred embodiment wherein thedispersed phenolic resin is a resole and the modifying agent is anaphthalene having a ionic pendant group X and two reaction-enablingsubstituents Y, the dispersed phenolic resin reaction product contains amixture of oligomers having stuctures believed to be represented by thefollowing formula III:

[0090] wherein X and Y are the same as in formulae Ia and Ib, a is 0 or1; n is 0 to 5; R² is independently —C(R⁵)₂— or —C(R⁵)₂—O—C(R⁵)₂—,wherein R⁵ is independently hydrogen, alkylol, hydroxyl, alkyl, aryl oraryl ether; and R³ is independently alkylol, alkyl, aryl or aryl ether.Preferably, R² is methylene or oxydimethylene and R³ is methylol. If6,7-dihydroxy-2naphthalenesulfonate, sodium salt is the modifying agent,X will be SO₃Na⁺ and each Y will be OH. It should be recognized that inthis case the hydroxy groups for Y will also act as chelating groupswith a metal ion.

[0091] The autodepositable component can be present in the compositionin any amount that provides for effective autodeposition. In general,the amount can range from 1 to 50, preferably 5 to 20, and morepreferably 7 to 14, weight percent, based on the total amount ofnon-volatile ingredients in the composition.

[0092] The control agent is any material that is able to improve theformation of an autodeposited coating on a metallic surface and,optionally, improve the formation of another autodeposited coatingapplied after the control agent-containing autodeposited coating.Addition of the control agent also increases the uniformity of thethickness of the autodeposited coating. The control agent-containingcomposition does not require an ambient staging period in order todevelop fully the coating. In other words, the metallic coatingconversion is complete upon drying of the coated substrate and anysubsequent coating, primer or adhesive compositions can be appliedimmediately after coating and drying of the control agent-containingcomposition. The control agent also must be compatible with the othercomponents of the composition under acidic conditions withoutprematurely coagulating or destabilizing the composition.

[0093] The control agent may be a nitro compound, a nitroso compound, anoxime compound, a nitrate compound, or a similar material. A mixture ofcontrol agents may be used. Organic nitro compounds are the preferredcontrol agents.

[0094] The organic nitro compound is any material that includes a nitrogroup (—NO₂) bonded to an organic moiety. Preferably, the organic nitrocompound is water soluble or, if water insoluble, capable of beingdispersed in water. Illustrative organic nitro compounds includenitroguanidine; aromatic nitrosulfonates such as nitro ordinitrobenzenesulfonate and the salts thereof such as sodium, potassium,amine or any monovalent metal ion (particularly the sodium salt of3,5-dinitrobenzenesulfonate); Naphthol Yellow S; and picric acid (alsoknown as trinitrophenol). Especially preferred for commercialavailability and regulatory reasons is a mixture of nitroguanidine andsodium nitrobenzenesulfonate.

[0095] The amount of control agent(s) in a multi-component compositionmay vary, particularly depending upon the amount of any acid in thecomposition. Preferably, the amount is up to 20 weight %, morepreferably up to 10 weight %, and most preferably 2 to 5 weight %, basedon the total amount of non-volatile ingredients in the composition.According to a preferred embodiment, the weight ratio of nitroguanidineto sodium nitrobenzenesulfonate should range from 1:10 to 5:1.

[0096] The organic nitro compound typically is mixed into thecomposition in the form of an aqueous solution or dispersion. Forexample, nitroguanidine is a solid at room temperature and is dissolvedin water prior to formulating into the composition.

[0097] The compositions of the invention may be prepared by any methodknown in the art, but are preferably prepared by combining and millingor shaking the ingredients and water in ball-mill, sand-mill, ceramicbead-mill, steel-bead mill, high speed media-mill or the like. It ispreferred to add each component to the mixture in a liquid form such asan aqueous dispersion.

[0098] The composition may be applied to a substrate surface by anyconventional method such as spraying, dipping, brushing, wiping,roll-coating (including reverse roll-coating) or the like, after whichthe composition typically is permitted to dry. Although conventionalapplication methods can be used, the composition can be applied viaautodeposition. The phenolic resin dispersion (A) of composition of theinvention enables autodeposition of the composition on anelectrochemically active metallic surface. Autodepositable compositionsusually are applied by dipping the metallic substrate or part into abath of the composition. The metal substrate rate can reside in themetal treatment composition bath for an amount of time sufficient todeposit a uniform of desired thickness. Typically, the bath residencetime is from about 5 to about 120 seconds, preferably about 10 to about30 seconds, and occurs at room temperature. The metal treatmentcomposition when it is applied to the metal substrate should besufficiently acidic to cause reaction with the metal to liberate themetallic ions. Typically, the pH of the metal treatment compositionshould be 1 to 4, preferably 1.5 to 2.5, when it is applied to the metalsubstrate. The composition typically is applied to form a dry filmthickness of 1 to 15, preferably 4 to 10 μm.

[0099] After simple forced air drying of a metal surface coated with thecontrol agent-containing composition the metal surface can beimmediately coated with another type of composition. The coated metalsubstrate typically is dried by subjecting it to heat and forced air.Depending upon the forced air flow, the drying usually occurs atapproximately 150-200° F. for a time period ranging from 30 seconds to10 minutes. The ambient staging period previously required after suchheated drying is no longer necessary. However, immediate subsequentcoating of the treated metal substrate is not required. Alternatively,the treated metal substrate can be stored for a period of time and thensubsequently coated with a different composition.

[0100] Although not required since a phenolic is incorporated in themetal treatment formulation itself, the metal treatment can be used incombination with a subsequent coating of a phenolic primer as mentionedabove. The combined metal treatment and phenolic primer providescorrosion resistance comparable to phosphatizing and a conventionalphenolic primer.

[0101] Preferably, the metal treatment composition serves as aprotective coating under a subsequently applied functionalautodepositable coating such as an adhesive primer or covercoat,particularly an adhesive primer or covercoat that is useful for bondingan elastomeric substrate to a metal substrate. A further advantage ofthe metal treatment is that it can activate a metal surface forautodeposition of the subsequently applied coating, primer or adhesivetopcoat that may include a dispersed phenolic resin as described above.Such a primer is described in more detail in co-pending, commonlyassigned U.S. Provisional Patent Application No. 60/072,779,incorporated herein by reference. In addition to enhancing the corrosionresistance as explained above, autodeposition activity of the subsequentcoating over the control agent-containing metal treatment composition issubstantially increased according to the invention.

[0102] Although preferred, the adhesive primer or covercoat applied overthe metal treatment does not have to be autodepositable. Conventional,non-autodepositable primers or covercoats can be used with the metaltreatment composition. Especially useful are known elastomer-to-metaladhesive primers or covercoats such as those described in U.S. Pat. Nos.3,258,388; 3,258,389; 4,119,587; 4,167,500; 4,483,962; 5,036,122;5,093,203; 5,128,403; 5,200,455; 5,200,459; 5,268,404; 5,281,638;5,300,555; and 5,496,884. Elastomer-to-metal adhesive primers andcovercoats are commercially available from Lord Corporation.

[0103] The composition according to the invention also can be utilizedby itself without any subsequent coating with an autodepositable primeror adhesive. Curing via crosslinking of the phenolic resin could occurthrough air oxidation or a surface activated chelating mechanism.

[0104] The invention will be described in more detail by way of thefollowing non-limiting examples. The failure mechanism for the testedbond is expressed in terms of percent. A high percent of rubber retained(R) on the metal coupon is desirable since this indicates that theadhesive bond is stronger than the rubber itself. Rubber-cement failure(RC) indicates the percentage of failure at the interface between therubber and the adhesive. Cement-metal failure (CM) indicates thepercentage of failure at the interface between the metal substrate andthe adhesive.

[0105] For the boiling water test the bonded test assemblies or couponswere prepared according to ASTM-D-429-B. The leading edge of each of theassemblies was stressed by suspending a two kg weight on the overlappingrubber tail and the assembly was then mounted in a fixture so that therubber tail was at an approximately 90° angle to the plane formed by thebonded interface. The stressed edge interface was exposed to boilingwater by immersing the coupon in boiling water for the indicated timeperiod. After this time, the coupons were removed from the boilingwater, allowed to cool and tested on either an Instron mechanical testerby pulling the rubber off the metal at a 45° angle stripping fixturewith a crosshead speed of 2 inches per minute or by manually peeling therubber from the metal substrate. The amount of rubber retained on thebonded area is recorded as a percentage as described above.

[0106] For the salt spray test the bonded test assemblies preparedaccording to ASTM-D-429-B were buffed on the edges with a grindingwheel. The rubber is then tied back over the metal with stainless steelwire so as to stress the bonded area. This exposes the bond line to theenvironment. The assemblies then are strung on stainless steel wire andplaced in a salt spray chamber. The environment inside the chamber is100° F., 100 percent relative humidity and 5 percent dissolved salt inthe spray, which is dispersed throughout the chamber. The assembliesremain in this environment for the indicated time period. Upon removal,the rubber is peeled manually from the metal substrate. The amount ofrubber retained on the bonded area is recorded as a percentage asdescribed above.

EXAMPLE-1—PREPARATION OF DISPERSED NOVOLAK RESIN

[0107] 40 g of 6,7-dihydroxy-2-naphthalenesulfonate, sodium salt(available from Andrew Chemicals), 136 g of a water soluble resole (madefrom formaldehyde and phenol, F/P ratio of 2.3, 80% solids andcommercially available from Schenectady under the trade designation HRJ11722), 50 g of tert-butyl catechol and 50 g of water were mixedtogether and steam heated for approximately three and one-half hoursuntil the mixture became very viscous. 220 g of resorcinol and 220 g ofwater were added followed by 6 g of phosphoric acid in 20 g of water.Steam heating was continued for another 40 minutes. 70 g of formalinthen was added while continuing steam heating resulting in aconcentrate. The concentrate was filtered and self-dispersed upon theaddition of 1730 g of water.

EXAMPLE-2—PREPARATION OF DISPERSED RESOLE RESIN

[0108] 160 g of 6,7-dihydroxy-2-naphthalenesulfonate, sodium salt(available from Andrew Chemicals), 1000 g of the HRJ11722 water solubleresole, and 50 g of water were mixed together and steam heated forapproximately three hours resulting in a very thick concentrate. 3600 gof water was added to the concentrate which then self-dispersed and wasfiltered.

EXAMPLE-3—PREPARATION OF DISPERSED NOVOLAK RESIN

[0109] 80 g of 6,7-dihydroxy-2-naphthalenesulfonate, sodium salt(available from Andrew Chemicals), 272 g of the HRJ 11722 water solubleresin, 100 g of tert-butyl catechol and 50 g of water were mixedtogether and steam heated for approximately three and one-half hoursuntil the mixture became very viscous. 440 g of resorcinol and 440 g ofwater were added followed by 12 g of phosphoric acid in 25 g of water.Steam heating was continued for another 40 minutes. 130 g of formalinthen was added while continuing steam heating resulting in aconcentrate. The concentrate was filtered and self-dispersed upon theaddition of 3085 g of water.

EXAMPLE-4—METAL TREATMENT WITH IMPROVED BONDING PERFORMANCE

[0110] The following ingredients were mixed together in indicated wetweight grams to obtain a metal treatment: Aqueous novolak dispersion ofExample 1 400 g Phosphoric acid 34 g Water 3100 g

[0111] The following ingredients were mixed together in indicated wetweight grams to obtain a coating/primer: Carbon black 7 g ZnO 60 gAqueous resole dispersion of Example 2 125 g Polyvinylalcohol-stabilized resole (BKUA 2370) 200 g Dichlorobutadienehomopolymer (VERSA TL/DOWFAX 150 g stabilized) Water 300 g

[0112] The metal treatment was spray applied to one set of warm steelcoupons. The treated coupons were dried at 150° F. The dried treatedcoupons were heated for 10 minutes at 160° F. and the coating/primer wasspray applied. The coupons then were heated at 150° F. for 15 minutes.With another set of coupons only the coating/primer was spray applied. Acommercially available aqueous adhesive covercoat (CHEMLOK®8210available from Lord Corporation) then was spray applied to the treated,primed coupons. Natural rubber was injection molded to the coupons at 1minute prebake and 5 minutes cure at 360° F. The bonded test assemblieswere subjected to the 40 hour boiling water test. The set of couponsthat were metal treated and primed exhibited a mean bonding performanceof 93R, 7CM under and the set of that were only primed exhibited a meanbonding performance of 47 R, 53 CM. When used in conjunction withCHEMLOK®8210, the metal treatment clearly improved the bondingperformance of the coating/primer.

EXAMPLE-5—AUTODEPOSITABLE METAL TREATMENT

[0113] The following ingredients were mixed together in indicated wetweight grams to obtain an autodepositable coating/primer: Carbon black21 g ZnO 180 g Aqueous resole dispersion of Example 2 400 g Polyvinylalcohol-stabilized resole (BKUA 2370) 600 g Dichlorobutadienehomopolymer (VERSA TL/DOWFAX 450 g stabilized) Water 1000 g

[0114] The following ingredients were mixed together in indicated wetweight grams to obtain a metal treatment used as an activatorcomposition: Aqueous novolak dispersion of Example 3 600 g Phosphoricacid 400 g Water 2700 g

[0115] Phosphatized steel coupons were dipped in a bath of the metaltreatment composition (4% solids) for 5 seconds. The metal treatmentcomposition formed a continuous wet film on the steel coupon surfaceindicating successful autodeposition. The treated coupons then weredried at 150° F. The dried treated coupons were then dipped in a bath ofthe coating/primer (20% solids) for 15 seconds. The coating/primercomposition formed a continuous wet film on the steel coupon surfaceindicating successful autodeposition. The coated coupons then were driedfor 15 minutes at 150° F. A one inch area then was masked off and acommercially available aqueous adhesive covercoat (CHEMLOK®8282available from Lord Corporation) was spray applied onto the treated andcoated coupons. The coupons then were prebaked for 30 seconds at 360° F.prior to bonding natural rubber for 5 minutes at 360° F. to the adhesivecoated coupon. This procedure was repeated, but the prebake was for 1minute at 340° F. and bonding was for 7 and one-half minutes at 340° F.The resulting test assemblies were subjected to the 4 hour boiling watertest and the salt spray test (500, 750 and 1000 hours). The results forall of the assemblies were 100% R bonding performance, no underbondcorrosion and very minor blistering in the unbonded portion that hadbeen masked off.

EXAMPLES-6-14—METAL TREATMENT THAT INCLUDES CONTROL AGENT

[0116] A phenolic novolak resin aqueous dispersion was made by mixingtogether 160 g of sodium salt of 6,7-dihydroxy-2-naphthalenesulfonate,544 g of a water soluble resole (made from formaldehyde and phenol, F/Pratio of 2.3, 80% solids and commercially available from Schenectadyunder the trade designation HRJ11722), 200 g of catechol and 200 g ofwater and steam heating for approximately two hours until the reactionmixture became very viscous and provided a clear dispersion. 880 g ofresorcinol and 500 g of water were added followed by 12 g of phosphoricacid in 10 g of water. Steam heating was continued for another 15minutes. 640 g of formalin (18.5% aqueous solution) then was added whilecontinuing steam heating resulting in a resin concentrate. Theconcentrate was filtered and self-dispersed upon the addition of 5900 gof water. This novolak dispersion was used to make a metal treatmentcomposition as described below.

[0117] A phenolic resole resin aqueous dispersion was made by mixingtogether 40 g of sodium salt of 6,7-dihydroxy-2-naphthalenesulfonate,250 g of the HRJ11722 resole resin, and 50 g of water and steam heatingfor approximately 2 hours until the reaction mixture became very viscousand provided a transparent dispersion. 800 g of water was added to theresulting resin concentrate which then self-dispersed and was filtered.This resole dispersion was used to make an autodepositable primer asdescribed below.

[0118] Aqueous metal treatment compositions according to the inventionwere prepared by mixing together at room temperature the followingingredients in the dry weight amounts in grams indicated in Table 1: thephenolic novolak resin aqueous dispersion described above (20% solids);aqueous solution phosphoric acid (5% solids); acrylonitrile-butadienelatex (available from B. F. Goodrich under the tradename HYCAR 1578X1,50% solids); nitroguanidine (“NGD”)(0.6% solids); sodiumnitrobenzensulfonate (“NBS”)(2.50% solids); and water. The amount ofadded water resulted in compositions having a total solids content of 6%or 8%. TABLE 1 Ingredient Ex. 6 Ex. 7 Ex. 8 Ex. 9 Ex. 10 Ex. 11 Ex. 12Ex. 13 Ex. 14 Phenolic 49.6 49.6 49.6 47.6 47.6 47.6 44.4 44.4 44.4resin Phosphoric 23.7 23.7 23.7 23.7 23.7 23.7 23.7 23.7 23.7 acid Latex23.7 23.7 23.7 23.7 23.7 23.7 23.7 23.7 23.7 NGD 1.00 0.75 0.50 1.671.25 0.83 2.73 2.05 1.36 NBS 2.00 2.25 2.50 3.33 3.75 4.17 5.47 6.156.84

[0119] Steel coupons (known as Q-Panels) were dipped in baths of thecompositions at room temperature for 15 seconds (for both 6% and 8%total solids content). After immersion the treated coupons wereimmediately dried at 200° F. for 5 minutes. Immediately after drying thetreated Q-panels were dipped for approximately 15 seconds in anautodepositable primer composition. The autodepositable primercomposition was prepared by mixing together 18 g carbon black, 60 g zincoxide, 75 g mica, 360 g aqueous phenolic resole resin dispersion, 540 gphenolic resole aqueous dispersion that incorporates a non-ionicprotective colloid, presumably polyvinyl alcohol, (available fromGeorgia-Pacific under the trade designation GP 4000), 600 gdichlorobutadiene homopolymer latex and 2800 g water to form acomposition having a solids content of 15%. The treated andprimer-coated Q-panels then were dried at 200° F. and then subsequentlybaked for 15 minutes at 320° F. Autodeposited coatings had formed on allthe panels.

[0120] The resulting panels were placed in a salt spray chamber in whichthe environment inside the chamber is 95° F, 100 percent relativehumidity and 5 percent dissolved salt in the spray, which is dispersedas a log continuously throughout the chamber. The panels were removedfrom the salt spray chamber after 300 hours and flexed on a ¼ inchmandrel. The crown of the flex was abraded by hand with SCOTCHBRITEabrasive cleaning pads to determine the durability of the coating thathad been subjected to the corrosive salt spray testing. The rating scalewas as follows: 0-massive delamination on simple flexing, extendingbeyond flexed area; 1-delamination of flexed area only; 2-somedelamination on flexing, abrasion removed remaining coating in flexedarea; 3-cracking of the coating, coating readily removed on abrasion;4-material could be abraded off but otherwise appeared to well-adhered;5-coating was unaffected by flex and abrasion. The results are shown inTable 2. TABLE 2 Solids Ex. Ex. Ex. Ex. Ex. content Ex. 6 Ex. 7 Ex. 8Ex. 9 10 11 12 13 14 6% 4 4 5 4 5 5 2 1 2 6% 5 5 5 5 5 3 2 1 2 8% 5 5 40 2 5 0 0 0

EXAMPLES 15-17—METAL TREATMENT THAT INCLUDES CONTROL AGENT

[0121] Aqueous metal treatment compositions according to the inventionwere prepared by mixing together at room temperature the ingredients inthe g wet weight amounts shown below in Table 3. The aqueous phenolicresin dispersion was the novolak dispersion described in connection withExamples 6-14. TABLE 3 Ingredient Example 15 Example 16 Example 17Phenolic resin dispersion 540 540 540 Phosphoric acid 540 540 540 Water1425 1350 1050 Acrylonitrile-butadiene latex 108 108 108 (HYCAR 1578)2,4-Dinitrobenzene sulfonate 228 0 0 (5% solids) Naphthol Yellow S (5% 0300 0 solids) Picric acid (1% solids) 0 0 600

[0122] Q-panels were dipped in baths of these compositions for theamount of time and temperature shown in Table 4 (“RT” represents roomtemperature) and then subjected to drying at 200° F., except for the 15second dip of Example 16 that was not dried. The treated panels thenwere immediately dipped in a bath of the autodepositable primercomposition described in Examples 6-14 for approximately 10 seconds,dried at 200° F. and then baked for 15 minutes at 320° F. With respectto the one sample wherein the metal treatment was not dried, applicationof the primer was done on a wet surface. Autodeposited coatings hadformed on each panel. The resulting panels then were subjected to thesalt spray testing for 250, 500 and 750 hours. After removal from thesalt spray chamber, the Q-panels were evaluated according to threetests. First, a portion of the panels was abraded by hand with aSCOTCHBRITE pad and the percentage amount of coating surface area thatwas unaffected was recorded. Second, a final portion of the panels wasflexed on a {fraction (5/16)} inch mandrel and then the crown of theflex was subjected to the pencil scratch test. The results of thesetests are displayed in Table 4. With respect to the flex test, “verypoor” is massive flaking, “poor” is visible flaking, “fair” is noflaking, but poor scratch on flexed areas. TABLE 4 250 hr 250 hr 500 hr500 hr 750 hr 750 hr Ex Dip Abrasion Flex Abrasion Flex Abrasion Flex 1510″ at RT 100%  Excellent 98% Excellent 96% Fair 15 5″ at 50° C. 100% Poor 95% Fair 99% Fair 16 10″ at RT 50% NA 10% NA 70% Poor 17 10″ at RT99% Poor 100%  Poor 98% Poor 15 15″ at RT 99% Excellent 98% Good 95%Poor

[0123] Aqueous metal treatment compositions according to the inventionwere prepared by mixing together at room temperature the followingingredients in g wet weight amounts: 360 g aqueous novolak dispersiondescribed in connection with Examples 6-14; 360 g phosphoric acid; 950 gwater; 152 g dinitrobenzene sulfonate (free acid); and 72 gflexibilizer. The flexibilizer in Example 18 was a styrene-butadienerubber emulsion commercially available from Reichold Chemical Co. underthe tradename TYLAC 97924; Example 19 was a chlorosulfonatedpolyethylene latex commercially available from Lord Corporation underthe tradename HYP 605; and Example 20 was a chlorinated natural rubberlatex.

[0124] Q-panels and degreased cold-rolled steel coupons were dipped forten seconds in the metal treatment composition (8% solids) of eachExample and then forced air dried at 200° F. The treated Q-panels andcoupons then were immediately dipped for 10 seconds in theautodepositable primer described above in connection with Examples 6-14.The Q-panels and coupons then were dried for five minutes at 200° F. andthen baked for 15 minutes at 320° F.

[0125] The resulting Q-panels were placed in the salt spray chamber for250 hours. After removal from the salt spray chamber the Q-panels wereabraded with SCOTCHBRITE pads and the percentage of coating not removedis indicated below in Table 5 under the heading “250 hrs SS”. TheQ-panels were also flexed on a {fraction (5/16)} inch mandrel. The crownof the flex was abraded by hand with SCOTCHBRITE abrasive cleaning padsto determine the durability of the coating that had been subjected tothe corrosive salt spray testing. The percentage of coating not removedacross the flexed radius is indicated below in Table 5.

[0126] A commercially available aqueous adhesive covercoat (CHEMLOK®8282available from Lord Corporation) was spray applied onto the treated andcoated coupons only. The coupons then were prebaked for 5 minutes at300° F. prior to bonding natural rubber for 16.5 minutes at 320° F. tothe adhesive coated coupon via compression molding. The bonded couponswere tested for primary adhesion performance (according to ASTM 429B) asdescribed above and the results are shown below in Table 5. The bondedcoupons also were flexed over a 1 inch mandrel, the rubber was peeledback by hand and the percentage of rubber retained on the crown of theflex is indicated in Table 5. TABLE 5 Example No. 250 hrs SS Q-panelflex Coupon flex Adhesion 18  98%  20%  95% R 100% R 19 100% 100% 100% R100% R 20 100% 100% 100% R 100% R

[0127] 200 g of resorcinol, 20 g of pyrogallol, 12 g of phosphoric acid(855 aqueous solution) and 220 g of water were mixed together and heatedto 95° C. When 95° C. was reached, 250 g of formalin (18.5% aqueoussolution) was fed to the reaction mixture over a period of 30 minutes.Steam heating was continued for another 15 minutes at which point themixture was slightly turbid and had a low viscosity (a sampleprecipitated out of solution upon dilution with water). 32 g of2-formylbenzenesulfonic acid (sodium salt, 75% moist solid) and 40 moreg of formalin then were added. Alter one hour and 15 minutes of steamheating the resin was very viscous. 580 g of water was added to theresin mixture and steam heating was continued until the resin wascompletely dispersible. Using essentially the same procedure5-formyl-2-furan sulfonate and 1-diazo-2-naphthol-4sulfonate stabilized(i.e., substituted for 2-formylbenzenesulfonic acid)resorcinol/pyrogallol novolak aqueous dispersions were prepared.

[0128] Three different metal treatment compositions (each containing oneof the different novolak dispersions) were made by mixing together thefollowing ingredients in wet weight amounts: 180 g dispersed novolakresin; 180 g phosphoric acid; 475 g water; 76 g dinitrobenzenesulfonate; and 36 g HYCAR latex. Q-panels were dipped into a bath of themetal treatment, dried for 3 minutes at 200° F., and then immediatelydipped for ten seconds into a bath of the primer composition describedin Examples 6-14. After removal from the primer bath, the Q-panels weredried at 200° F., and baked for fifteen minutes at 320° F. The resultingQ-panels had coatings varying in thickness from 0.90 to 1.06 milsindicating the formation of an autodeposited coating. The coatedQ-panels

[0129] were placed in the salt spray chamber for 250 and 500 hours,respectively. The Q-panel coatings were abraded with a SCOTCHBRITE padand the percentage of coating not removed is indicated below in Table 6.TABLE 6 Example No. Novolak Modifying Agent 250 hr SS 500 hr SS 212-formylbenzenesulfonic acid 98% 97% 22 5-formyl-2-furan sulfonate 96%94% 23 1-diazo-2-naphthol-4-sulfonate 99% 96%

What is claimed is:
 1. An aqueous metal surface treatment compositioncomprising the following ingredients: (A) an aqueous dispersion of aphenolic novolak resin that includes a reaction product of (i) aphenolic resin precursor; (ii) a modifying agent wherein the modifyingagent includes (a) at least one functional moiety that enables themodifying agent to react with the phenolic resin precursor; and (b) atleast one ionic moiety; and (iii) at least one multi-hydroxy phenoliccompound; and (B) an acid.
 2. An aqueous composition according to claim1 wherein the modifying agent is an aromatic compound.
 3. An aqueouscomposition according to claim 1 wherein the ionic moiety of themodifying agent is sulfate, sulfonate, sulfinate, sulfenate oroxysulfonate and the dispersed phenolic novolak has a carbon/sulfur atomratio of 20:1 to 200:1.
 4. An aqueous composition according to claim 1wherein the phenolic resin precursor comprises a resole.
 5. An aqueouscomposition according to claim 1 wherein the modifying agent is selectedfrom a sulfonated naphthalene, a sulfonated formyl group-containingcompound or a sulfonated diazo compound.
 6. An aqueous compositionaccording to claim 1 wherein the reaction-enabling moiety is selectedfrom hydroxy, hydroxyalkyl, formyl or diazo.
 7. An aqueous compositionaccording to claim 1 wherein the modifying agent comprises a structurerepresented by formula Ia or Ib:

wherein X is the ionic moiety; Y is the reaction-enabling moiety; Z is achelating substituent; L¹ is a divalent linking group; a is 1; b is 1 to4; m is 0 or 1; and c and d are each independently 0 to 3, providedthere are not more than 4 substituents on each aromatic ring.
 8. Anaqueous composition according to claim 1 wherein the ionic moiety is asulfonate and the reaction-enabling moiety is selected from hydroxy orhydroxyalkyl.
 9. An aqueous composition according to claim 1 wherein themodifying agent comprises dihydroxy naphthalenesulfonate.
 10. An aqueouscomposition according to claim 9 wherein the resole precursor comprisesa resole.
 11. An aqueous composition according to claim 10 wherein themulti-hydroxy phenolic compound is selected from resorcinol orpyrocatechol.
 12. An aqueous composition according to claim 1 whereinthe multi- hydroxy compound is selected from resorcinol, pyrocatechol,hydroquinone, pyrogallol, 1,3,5-benzenetriol and tert-butyl catechol.13. An aqueous composition according to claim 1 wherein the acidcomprises phosphoric acid.
 14. An aqueous composition according to claim11 wherein the acid comprises phosphoric acid.
 15. An aqueouscomposition according to claim 1 wherein the pH of the composition is 1to
 4. 16. An aqueous composition according to claim 1 further comprisinga flexibilizer ingredient.
 17. An aqueous composition according to claim16 wherein the flexibilizer is selected from (poly)butadienie, neoprene,styrene-butadiene rubber, nitrile rubber, halogenated polyolefin,acrylic polymer, urethane polymer, ethylene-propylene copolymer rubber,ethylene-propylene-diene terpolymer rubber, styrene-acrylic copolymer,polyamide and poly(vinyl acetate).
 18. An aqueous composition accordingto claim 17 wherein the flexibilizer is selected from halogenatedpolyolefin, nitrile rubber and styrene-acrylic copolymer.
 19. An aqueouscomposition according to claim 14 further comprising a flexibilizeringredient selected from halogenated polyolefin, nitrile rubber andstyrene-acrylic copolymer.
 20. An aqueous composition according to claim1 wherein the composition is autodepositable on the metal surface. 21.An aqueous composition according to claim 1 wherein the dispersednovolak comprises a structure represented by:

wherein X is the ionic moiety; Y is the reaction-enabling moiety; a is 0or 1; n is 0 to 5 and R⁴ is independently hydroxyl, alkyl, aryl,alkylaryl or aryl ether.
 22. An aqueous metal surface treatmentcomposition formed by combining: (A) an aqueous dispersion of a phenolicnovolak resin that includes a reaction product of (i) a phenolic resinprecursor; (ii) a modifying agent wherein the modifying agent includes(a) at least one functional moiety that enables the modifying agent toreact with the phenolic resin precursor; and (b) at least one ionicmoiety; and (iii) at least one multi-hydroxy phenolic compound; and (B)an acid.
 23. A method for providing a protective coating on a metallicsurface comprising applying an aqueous composition to the surfacewherein the composition comprises the following ingredients: (A) anaqueous dispersion of a phenolic novolak resin that includes a reactionproduct of (i) a phenolic resin precursor; (ii) a modifying agentwherein the modifying agent includes (a) at least one functional moietythat enables the modifying agent to react with the phenolic resinprecursor; and (b) at least one ionic moiety; and (iii) at least onemulti-hydroxy phenolic compound; and (B) an acid.
 24. A method accordingto claim 23 wherein the metallic surface is dipped into a bath of thecomposition so that the composition autodeposits the protective coatingon the metal surface.
 25. A method according to claim 23 wherein themodifying agent is selected from a sulfonated naphthalene, a sulfonatedformyl group-containing compound or a sulfonated diazo compound.
 26. Amethod according to claim 23 wherein the modifying agent comprisesdihydroxy naphthalenesulfonate, the phenolic resin precursor comprises aresole, and the multi-hydroxy phenolic compound is selected fromresorcinol or pyrocatechol.
 27. A method according to claim 23 whereinthe acid comprises phosphoric acid.
 28. A method according to claim 26wherein the acid comprises phosphoric acid.
 29. A method according toclaim 23 wherein the composition further comprises a flexibilizeringredient.
 30. A method according to claim 29 wherein the flexibilizeringredient is selected from halogenated polyolefin, nitrile rubber andstyrene-acrylic copolymer.
 31. A method according to claim 28 whereinthe composition further comprises a flexibilizer ingredient selectedfrom halogenated polyolefin, nitrile rubber and styrene-acryliccopolymer.
 32. An autodeposition composition comprising the followingingredients: an autodepositable component; and at least one organicnitro compound.
 33. A composition according to claim 32 wherein theorganic nitro compound is selected from nitroguanidine, aromaticnitrosulfonate, Naphthol Yellow S or picric acid.
 34. A compositionaccording to claim 33 comprising nitroguanidine and an aromaticnitrosulfonate as organic nitro compounds.
 35. A composition accordingto claim 34 wherein the aromatic nitrosulfonate comprises a nitro ordinitro benzenesulfonate.
 36. An autodeposition composition comprisingthe following ingredients: a phenolic resin that is the reaction productof a phenolic compound with an aldehyde compound; and at least onecontrol agent selected from a nitro compound, a nitroso compound, anoxime compound and a nitrate compound.
 37. A composition according toclaim 36 wherein the phenolic resin comprises an aqueous dispersion of aphenolic novolak resin that includes a reaction product of (i) aphenolic resin precursor; (ii) a modifying agent wherein the modifyingagent includes (a) at least one functional moiety that enables themodifying agent to react with the phenolic resin precursor; and (b) atleast one ionic moiety; and (iii) at least one multi-hydroxy phenoliccompound.
 38. A composition according to claim 37 wherein the controlagent comprises an organic nitro compound.
 39. A composition accordingto claim 36 wherein nitroguanidine and an aromatic nitrosulfonate arecontrol agents.
 40. A composition according to claim 39 wherein thearomatic nitrosulfonate comprises a nitro or dinitro benzenesulfonate.41. A composition according to claim 36 further comprising a phosphoricacid ingredient.
 42. A composition according to claim 36 furthercomprising a flexibilizer ingredient.
 43. A composition according toclaim 42 wherein the flexibilizer ingiedient is selected fromhalogenated polyolefin, nitrile rubber and styrene-acrylic copolymer.44. A composition according to claim 36 wherein the control agent is,present in an amount of up to 20% by weight based on the total weight ofnon-volatile ingredients in the composition.
 45. A composition accordingto claim 36 wherein the modifying agent is selected from a sulfonatednaphthalene, a sulfonated formyl group-containing compound or asulfonated diazo compound.
 46. A composition according to claim 45wherein the modifying agent comprises a dilhydroxy naphthalenesulfonate.47. A composition according to claim 46 wherein the phenolic resinprecursor comprises a resole, the multi-hydroxy phenolic compound isselected from resorcinol, pyrocatechol, hydroquinone, pyrogallol,1,3,5-benzenetriol or tert-butyl catechol, the control agent comprisesan organic nitro compound and further comprising phosphoric acid and aflexibilizer.
 48. An aqueous autodeposition composition formed bycombining: (a) an aqueous dispersion that includes a phenolic resin thatis the reaction product of a phenolic compound with an aldehydecompound; and (b) at least one control agent selected from a nitrocompound, a nitroso compound, an oxime compound and a nitrate compound.49. A method for providing a protective coating on a metallic surfacecomprising applying an aqueous autodeposition composition to the surfacewherein the composition comprises the following ingredients: anautodepositable component; and at least one organic nitro compound. 50.A method for providing a protective coating on a metallic surfacecomprising applying an aqueous autodeposition composition to the surfacewherein the composition comprises the following ingredients: a phenolicresin that is the reaction product of a phenolic compound with analdehyde compound; and at least one control agent selected from a nitrocompound, a nitroso compound, an oxime compound and a nitrate compound.51. A method according to claim 50 wherein the metallic surface isdipped into a bath of the composition so that the compositionautodeposits the protective coating on the metal surface.
 52. A methodaccording to claim 50 further comprising a subsequent step of applying asecond autodeposition composition.
 53. A method according to claim 50further comprising a subsequent step of applying an adhesive primer oradhesive covercoat.
 54. A method according to claim 50 wherein thecontrol agent comprises an organic nitro compound.
 55. A methodaccording to claim 50 wherein nitroguanidine and an aromaticnitrosulfonate are the control agents.
 56. A method according to claim55 wherein the aromatic nitrosulfonate comprises a nitro or dinitrobenzenesulfonate.
 57. A method according to claim 50 wherein thecomposition further comprises a phosphoric acid ingredient.
 58. A methodaccording to claim 50 wherein the composition further comprises aflexibilizer ingredient.
 59. A method according to claim 58 wherein theflexibilizer ingredient is selected from halogenated polyolefin, nitrilerubber and styrene-acrylic copolymer.
 60. A method according to claim 50wherein the control agent is present in an amount of up to 20% by weightbased on the total weight of non-volatile ingredients in thecomposition.
 61. A method according to claim 50 wherein the modifyingagent is selected from a sulfonated naphthalene, a sulfonated formylgroup-containing compound or a sulfonated diazo compound.
 62. A methodaccording to claim 61 wherein the modifying agent comprises a dihydroxynaphthalenesulfonate.
 63. A method according to claim 62 wherein thephenolic resin precursor comprises a resole, the multi-hydroxy phenoliccompound is selected from resorcinol, pyrocatechol, hydroquinone,pyrogallol, 1,3,5-benzenetriol or tert-butyl catechol, the control agentcomprises an organic nitro compound and further comprising phosphoricacid and a flexibilizer.